Traditionally,the 1 technique per class and then sparring is the Brazilian Way,and the active drilling of techniques with less sparring is the American way.
Obviously there are exceptions to this generalisation though.

The answer is that some students will learn faster the first way and others will learn faster the second way-It depends on the student.

The Brazilian way of 1 technique per class is great because it's almost guarenteed that everyone will remember the technique the next day.whereas if multiple techniques are shown it becomes more difficult to retain all the information.(We've all been to seminars and not remembered more than a quarter of what was shown).

The japanese way of Uchi Komi (repetition) is an excellent way of teaching
(100 arm bars from guard each side for example),because the technique becomes second nature.

In answer to your question,there is no answer that fits all students.As an instructor i try and gauge the class size,the belt levels and plan over the course of many months what i want the class to achieve as a whole.

I also use all 3 methods mentioned above to stop guys getting bored and to make sure all students with different personalities and learning abilities are catered for.

For instance,sometimes i will shock the class by doing a 10 minute warm up then sparring for 1hr 45 minutes with no techniques at all.
Other times i will teach up to 6 techniques then only have 4x6 minute rounds of sparring.And sometimes they will do multiple repetitions of arm bars and triangles for the whole class,but always sparring at the end.
I also repeat classes over a couple of months on rotation so if some students can't learn and remember a complex technique after being taught it once then they will get taught the same class again a week or so later,and the guys that did retain the information get another class to drill the technique and fine tune it.

Basically,as an instructor it's all about knowing your students,their ability and strengths and weaknesses and working with them to better their games.

That comes from having long term goals and plans for them which can be assessed by their performances in competition and sparring.

I have a series of about 20 or 30 drills that I use in rotation, some feature every class, some every 2 or 3 and I have found it a very good (if repetitive) way of teaching.

Sometimes I may have a class that is just sparring and sometimes I will show a lot of techniques but if I had to choose one way of getting students to improve quickly I would concentrate on drilling. (although there should always be some sparring)

(turn heather up ALOT brazilian tempature, will make everyone tired and shut up, also less injuries)

applied warming up (note i use non gay self defence also in warming up)
i dont do jumping jacks, running most of the time, push ups, sit ups. i believe this can be done beter.
pummeling, grip drlls, penetration shots, uchi komi throws, sit outs, guard retention drills

3 moves from 1 position.
Spar 3 round changing with partners starting in position we just did. submit or escape goal.
Do 1/2/3 escapes from that same position again.
spar another 3 rounds
and free sparring.
end up with 25 armbars, traingles, omoplatas.